JP2853356B2 - High frequency heating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heating device such as a microwave oven.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional high-frequency heating apparatus comprises a rectifier circuit composed of a rectifier 2, an inductor 3, and a capacitor 4 for rectifying electric power supplied from a commercial power supply 1 into a DC voltage, and a capacitor 5; , A transistor 6, a diode 7, and a step-up transformer 8, a high-voltage capacitor 9, high-voltage diodes 10 and 11,
A high-voltage rectifier circuit, a magnetron 12 receiving the output of the high-voltage rectifier circuit and generating a high-frequency radio wave, a control circuit 13 for controlling the operating frequency of the transistor 6, and a relay 14 for controlling and heating the control circuit 13. A heating control unit 15 for giving a command, a start control unit 16 for giving a command for obtaining a radio wave output larger than a continuous rated output for a predetermined time when the high-frequency heating device is started, and the like are provided.

FIGS. 6A and 6B show a terminal voltage Vac of a capacitor 4 which is an input voltage of an inverter circuit, and FIG.
7 is an envelope waveform of an anode current Ia of the magnetron 12. The actual Ia waveform is a high-frequency current waveform having an envelope as shown in the figure, but during the period when the magnetron 12 is oscillating, as shown by a broken line in the figure, Va
This is only when c is equal to or higher than the voltage corresponding to the threshold voltage of the magnetron 12. That is, in order to prevent the input power factor of the input terminal of the high-frequency heating device (that is, the AC terminal of the rectifier 2) from lowering, the terminal voltage of the capacitor 4 must have a voltage waveform as shown in FIG. Therefore, the magnetron 12 performed an intermittent oscillation operation as shown in FIG.

[0004] In addition, many commercial power outlets in ordinary households are rated at 15A, and the power wiring in the household is often rated at 20A. Therefore, the maximum current consumption of high-frequency heating equipment such as a microwave oven is 13 to 14A. I had to keep it around. This is because even if the indoor wiring current capacity is 20 A, there are devices that are used simultaneously, such as a rice cooker and a toaster, and the current consumption is often 6 to 7 A.

Therefore, in the conventional high-frequency heating device, as shown in FIG. 6A, the oscillation operation period of the magnetron 12 is about one half of the entire operation period, and the input current from the commercial power supply or the like is reduced. Due to restrictions, for example, 10
In the case of a device having an AC power supply specification of 0 V, its input power is usually limited to 1.2 to 1.3 kW. Therefore, the output power of the conventional high-frequency heating device is almost 600
It is limited to W, and a maximum output of 700 W with a short-time rating is the maximum possible output, and only a high-frequency heating device with such a radio output has been put to practical use.

As shown in FIG. 7, the output of the commercial power supply 1 is supplied to a high voltage circuit 20 including a high voltage transformer and a high voltage rectifier circuit.
A high-frequency heating apparatus has been proposed in which a DC high voltage is applied to drive the magnetron 12 and the output of the battery 21 is converted by the converter 22 and supplied to the magnetron 12. This is switched (or supplied at the same time) by the switch 23, and the commercial power supply 1 and the battery 21 are switched.
This drives the magnetron 12, and realizes this by separately providing the high voltage circuit 20 and the converter 22.

Therefore, the input current from the commercial power supply can be suppressed to a small level by a high-frequency heating device configured to perform such switching control. The configuration is large and complicated due to the need for storage batteries, etc.
It had to be expensive.

[0008]

However, in the above conventional configuration, the input current from the commercial power supply is limited,
Only a radio wave output equivalent to that can be obtained, and it has been difficult to further enhance the high-speed heating (high-speed cooking) feature of the high-frequency heating device. In addition, even if a conventional configuration using a battery is used, the whole apparatus becomes large-sized, expensive, and requires switching of a high-voltage circuit. It is difficult to realize, and the input current from an external power source such as a commercial power source must be limited. Therefore, for example, with a 100 Vac input voltage, the problem that the radio wave output is limited to about 600 W cannot be solved. Therefore, it is extremely difficult to realize a high-frequency heating device which is not limited by the current capacity of an external power supply such as a commercial power supply, has a higher high-frequency output, can realize high-speed heating (cooking), and has a compact and lightweight structure. However, there has been a problem that a high-frequency heating device suitable for modern eating habits requiring higher-speed cooking cannot be realized.

[0009] The present invention solves the above-mentioned problems, and is intended for commercial use.
Without being limited by the input current of the power supply,
A large high-frequency output can be obtained without increasing the maximum current value of the anode current of the tron, and the characteristics of the high-frequency heating device are remarkably improved, and at the same time, the size and the complexity are prevented. It is an object of the present invention to provide a high-frequency heating device capable of exhibiting extremely efficient performance while suppressing price increase.

The present invention has the following configuration to achieve the above object. That is, rectify the commercial power
A power conversion unit that converts power supplied from an external power supply that outputs a pulsating voltage obtained by: a radio wave radiation unit that receives an output of the power conversion unit and radiates high-frequency power to a heating chamber;
A heating control unit that controls the heating state of the object to be heated, a storage battery that is configured to supply power to the power conversion unit and that is installed inside or on the outer wall of the housing, and that any command signal from the heating control unit A short-time high-output control unit that controls the converted power of the power conversion unit to be larger than the steady-state power in the continuous operation state for a predetermined period of time, wherein the short-time high-output control unit is To supply the power of both the external power source and the energy source of the storage battery to the power conversion unit, and the radio wave output becomes larger than the steady radio wave output in the continuous operation state for a predetermined time according to the command signal. It is configured to perform such control.

Further, in response to a start command signal from the heating control unit, the short-time high-output control unit controls the power conversion unit to reduce the power of both energy sources of the external power source and the storage battery to the power source. The power is supplied to the converter, and during a predetermined time when the high-frequency heating device is started, the short-time high-power controller makes the converted power of the power converter larger than the steady power in the continuous operation state. The radio wave output at the time of startup for a predetermined time according to the command signal is controlled to be larger than the steady radio wave output in the continuous operation state.

[0012] Further, a charging means for obtaining electric power from a commercial power supply and charging the storage battery is provided.

Still further, the storage battery is charged by the charging means when the operation of the power converter is stopped.

[0014]

According to the present invention, with the above-described configuration, the power from the storage battery in addition to the power from the external power supply is converted into power by the same power conversion unit and supplied to the radio wave radiation unit.
Thus, a current of a desired magnitude can be generated for a predetermined short time without being limited by the input current from the external power supply.

Further, since a means for charging a storage battery by obtaining power from a commercial power supply is provided, a current output of a desired magnitude can be generated. In addition, since there is a means for charging the storage battery during the operation stop time of the power conversion unit, the storage battery can always supply the maximum power.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 31 denotes a commercial power supply, which supplies electric power to the high-frequency heating device 32 from outside. The high-frequency heating device 32 includes a power conversion unit 33 that converts the power,
It has a radio wave radiating unit 34 that receives the power converted by the power converting unit 33, generates high-frequency radio waves such as microwaves, and supplies the high-frequency radio waves to a heating chamber (not shown). Further, the power converter 33 includes, for example, the power converter 35 and the converter controller 3.
6. The high-frequency heating device 32 further includes a storage battery 37, and the output is supplied to the power converter 35 of the power converter 33 via the booster 38. The storage battery 37 may be built in the housing of the high-frequency heating device 32, or may be provided outside the housing so that it can be easily replaced. This storage battery 37 is supplied to an input unit 40 by a charging unit 39.
It is configured to be charged by energy supplied from the external power supply 31, and the storage battery 37 can be used semi-permanently without replacement.

The heating control unit 41 includes a short-time high-output control unit 4
2, and controls the converter control unit 36 of the power conversion unit 33 to perform a predetermined short time (for example, 1 minute to 5 minutes) according to an operation command from an operation unit (not shown) or a cooking command based on the operation command.
During this period, the conversion power of the power conversion unit 33 is made larger than the maximum allowable power in continuous operation.

At this time, the heating control section 41 supplies the electric power of the storage battery 37 to the electric power conversion section 33 in addition to the electric power from the external power supply by controlling the boosting section 38, for example. Therefore, while maintaining the input current from the external power supply 31 at a predetermined value (for example, 14 A), a desired predetermined large power is applied to the power conversion unit 33, and the output radio wave from the radio wave radiation unit 34 is set to an extremely strong level. can do. For example, assuming that the external power supply 31 is a commercial power supply of 100 V and the input current is 12 to 13 A, the conventional technology can supply only about 1.2 to 1.3 kW of power to the power conversion unit 33. The output was only about 600W. However, in the high-frequency heating device 32 of FIG. 1 embodying the present invention, in addition to the power supplied from the external power supply 31, it is possible to supply the power supplied from the storage battery 37 to the power converter 33 together. Therefore, 1.3 kW from the external power supply 31 and 0.7 kW from the storage battery 37
With a configuration that supplies kW of power, the power conversion unit 33 converts the total power of 2.0 kW into power, and as a result, the power output of the radio wave radiating unit can be as large as 1000 W. .

That is, according to the configuration shown in FIG.
It is possible to realize a high-frequency heating device in which the high-speed heating (cooking) performance is doubled or more than the conventional one without increasing the input current from the first. Moreover, the short-time high-output control unit 42 performs such high-radio-wave output control only during a heating time within a predetermined time (for example, three minutes) according to an arbitrary command from the heating control unit 41. The cooling configuration of 32 does not need to guarantee this large output (1000 W) as the rated output in continuous operation. In other words, the heat generated by the resistance loss increases but is short, so that the temperature of each component does not exceed the temperature at the rated output. Therefore, it is not necessary to make the heat resistance of each component such as the high-voltage transformer and the power semiconductor excessively high, and a high-frequency heating device having such a large radio wave output can be realized very economically.

FIG. 2 is a diagram for explaining the state of the short-time high-power control. FIG. 2A shows the temperature rise Δ of the heat-generating component.
T, FIG. 2B shows the radio wave output P ₀ of the conventional high frequency heating device, and FIG. 3C shows the radio wave output P ₁ of the high frequency heating device of the present invention.

The temperature rise line α in FIG. 2A is shown in FIG.
Shows a temperature rise curve in the conventional case of FIG. 1, and shows a temperature rise ΔT1 caused by continuous operation at the rated output P _{0 for} t1 time, and the power of the power converter that can obtain such an output P ₀ is continuously operated. It is the steady power at the time. Therefore, the cooling configuration of the high-frequency heating device and the heat resistance of each heat-generating component have been determined in order to guarantee the temperature rise ΔT1 under the steady power during the continuous operation. If a heating device having a high radio wave output as in the present invention is constructed based on such a concept, the heating device must be very expensive and large in size in order to realize the cooling structure and heat resistance performance. On the other hand, in actual heating cooking, cooking in a short heating time is often sufficient, and most of cooking in a high-frequency heating device with a radio wave output of 500 W is about 1 to 3 minutes. Therefore, in the case of 1000 W radio wave output as in this embodiment,
Half the heating time is sufficient. In consideration of this point, the present invention is provided with the short-time high-power control unit 42. FIG. 2C shows the state of the short-time high-power control, in which the radio wave output P _{1 is set} to 1000 for an arbitrary time t3.
W is controlled. If the case where the cooking time is t2 time longer than this t3 time occurs, FIG.
As shown in, the radio wave output P ₁ after the elapse of the time t3 10
It is configured to perform control so as to decrease from 00W to 600W. By adopting such a configuration, most heating cooking can be performed with a large radio wave output, which was hardly possible with the conventional technology of, for example, 1000 W, without excessive heat performance and cooling design. High speed heating cooking performance can be exhibited. In the present embodiment, the short-time high-output control is performed at the time of starting the apparatus. However, the present invention is not limited to this, and the short-time high-output control is performed at any time during cooking. It is good also as a structure which performs.

FIG. 3 is a circuit diagram showing a more detailed configuration of one embodiment of the present invention shown in FIG. 1, and components having the same reference numerals as those in FIG. 1 are corresponding components.

FIG. 3 is a circuit diagram of a high-frequency heating device in the case where a commercial power supply 31 is used as an external power supply. The power converter 35 has a full-wave rectified waveform DC consisting of a diode bridge 50, an inductor 51 and a capacitor 52. Power and
An inverter including a resonance capacitor 53, a step-up transformer 54, a transistor 55, and a diode 56, a high-voltage rectification circuit including a capacitor 57, diodes 58 and 59, and a resonance capacitor 60, and inductors 61 and 62.
And a heater circuit for supplying a heater current to the magnetron 63 through the heater circuit. The radio wave radiating unit 34 is configured by a magnetron 63, controls the switching frequency of the transistor 55 by the converter control unit 36 to operate the inverter, is supplied with high voltage power and heater power, oscillates, and radiates radio waves to the heating chamber. . Although the details of the basic power conversion operation of the inverter are well known and omitted, the converter control unit 36 uses the signals of the current transformers 65 and 66 based on the signals of the heating control unit 41 including the microcomputer 64 and the like. While controlling the radio wave output, the transistor 55 is controlled to adjust the magnitude of the radio wave output.

The storage battery 37 preferably has a voltage of about 24 V from the viewpoint of safety and manufacturing cost.
The power is supplied to the power converter 35 via the. The boosting unit 38 includes a boost inductor 67 with a tap,
It is composed of capacitors 68 and 69, a transistor 70, diodes 71 and 72, and a control circuit 73.
The C / DC converter is a C / DC converter, and the detailed description of the operation is omitted, but by controlling the on / off ratio of the transistor 70 with the control circuit 73, the terminal voltage of the capacitor 69 (that is, the DC output voltage) can be adjusted.

For example, when the heating operation of the high-frequency heating device is started, the heating control unit 41 closes the relay contacts 74 and 75 and sends a short-time high-output operation command to the converter control unit 36 and the control circuit 73 of the boosting unit 38. give. Thereby, the inverter which forms the center of the power conversion function of the power converter 35 receives the sum power of the power from the commercial power supply 31 and the power from the battery boosted by the booster to perform the power conversion operation.

FIGS. 4 (a), (b), (c) and (d)
Is the output voltage Va of the diode bridge 50, respectively.
c, output voltages Vdc, Vac and Vdc of diode 72
, And the anode current Ia of the magnetron 63. FIG.
As is clearer, Vac is at a certain voltage (eg, 100
V) Vdc is supplied to the inverter in the following cases, and Vac is supplied in other cases. Therefore, the average value of the anode current Ia of the magnetron 63 can be approximately doubled without increasing the maximum value, and the radio wave output can be approximately doubled by supplying Vdc. Since such a configuration has an advantage that the average value can be increased without increasing the maximum value, it is a very desirable condition for the semiconductor such as the transistor 55 constituting the power converter 35, the resonance capacitor 53, and the like. About twice the power conversion is possible using relatively low voltage and current ratings and low cost components. Further, with the configuration in which Vdc is supplied only when the instantaneous voltage of the commercial power supply 31 is low, Vdc is reduced to the voltage Vac from the commercial power supply while maintaining the power factor of the input power from the commercial power supply 31 at a relatively high value. Since the superimposition can be performed, it is possible to provide a high-frequency heating device having a high input power factor even when such high output control is performed.

As shown in FIG. 4B, the operation of the boosting section 38 may be interrupted and synchronized in synchronization with Vac. However, if the capacity of the smoothing capacitor 69 is made sufficiently large, the boosting section 38 will not be operated.
Does not require intermittent operation, and can achieve the same performance even when it is operated continuously. That is, Vdc is set to, for example, 10
The voltage may be a constant voltage of 0V. In this case, instead of increasing the capacity of the capacitor 69, the maximum current and the maximum voltage of the transistor 70 and the like can be kept low. Therefore, when the power supplied from the storage battery 37 is large, this is advantageous in terms of price or conversion efficiency. Is more desirable.

When the operation of the high-frequency heating device is stopped, the heating control unit 41 opens the relay contacts 74 and 75,
Is closed, the charging circuit (charging unit) 39 is operated, and the storage battery 37 is operated.
Is charged and electric energy is automatically stored until the next heating operation. The charging circuit 39 converts the DC voltage obtained by the diode 77 and the capacitor 78 into a transistor 79, diodes 80 and 81, an inductor 82,
The storage battery 3 is controlled by the capacitor 83 and the control circuit 84.
A well-known step-down DC /
Since this is a DC converter whose output voltage can be arbitrarily adjusted by the on / off ratio of the transistor 79, a detailed description of the operation is omitted.

With such a configuration, the power conversion circuit 35
Since the power supply from the commercial power supply 31 to the charging circuit 39 can be reduced to zero during the operation of, the maximum power that can be supplied from the commercial power supply 31 is converted into power and a desired large radio wave output can be obtained.

[0031]

As described above, according to the high frequency heating apparatus of the present invention, the following effects can be obtained.

(1) In addition to the power from the external power, the combined power from the storage battery is supplied to the radio wave radiating section, so that the desired large radio wave output can be arbitrarily set without being limited by the input current from the external power supply. It can occur for a predetermined time. Therefore, cooking can be performed in a single hour.

(3) Since the power from the external power supply and the storage battery is converted by the same power converter and supplied to the radio wave radiator, the two powers can be combined with a simple configuration. Also, storage batteries
Is superimposed when the voltage of the commercial power supply is low
Therefore, the anode current of the magnetron and the
Obtain large electric wave output without increasing large current and voltage
It can make the cooling performance of the high-frequency heating device excessive
It can be realized without doing.

(3) It is sufficient to supply a desired large high-frequency output for a short time at a predetermined arbitrary heating timing corresponding to the actual use state, so that the cooling performance and heat resistance of the high-frequency heating device are made excessive. Therefore, it is possible to reduce the size, the complexity, and the excessive quality.

(4) Since a charging means is provided for charging the storage battery by obtaining electric power from a commercial power supply, a desired large radio wave can be obtained without replacing the storage battery for a long time without being limited by the input current from the external power supply. Output can be generated.

(5) Since the storage battery is charged by the charging means when the operation of the power converter is stopped, all the power supplied from the external power supply can be supplied to the power converter during the operation of the power converter. A desired large radio wave output can be generated while supplying power from an external power supply.

[Brief description of the drawings]

FIG. 1 is a block diagram of a high-frequency heating device according to an embodiment of the present invention.

2A is a graph showing a temperature rise of the high-frequency heating device shown in FIG. 1; FIG. 2B is a graph showing a radio-wave output characteristic of the conventional high-frequency heating device;

FIG. 3 is a circuit diagram showing a more detailed configuration of FIG. 1;

4A is a supply voltage waveform diagram from a commercial power supply in the high-frequency heating device of FIG. 3; FIG. 4B is a supply voltage waveform diagram from a storage battery in the high-frequency heating device of FIG. 3; (D) Envelope diagram of magnetron anode current waveform in the high-frequency heating device of FIG. 3

FIG. 5 is a circuit diagram of a conventional high-frequency heating device.

6A is an input voltage waveform diagram of the high-frequency heating device of FIG. 5; FIG. 6B is an envelope diagram of an anode current waveform of a magnetron in the high-frequency heating device of FIG. 5;

FIG. 7 is a block diagram of another conventional high-frequency heating device.

[Explanation of symbols]

 Reference Signs List 31 external power supply 32 high frequency heating device 33 power conversion unit 34 radio wave radiating unit 37 storage battery 39 charging means 41 heating control unit 42 short time high output control unit

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Daisuke Villa 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Yuji Nakabayashi 1006 Oji Kadoma Kadoma City, Osaka Matsushita Electric Industrial Inside the company (72) Inventor Takahiro Matsumoto 1006 Kadoma Kadoma, Osaka Pref.Matsushita Electric Industrial Co., Ltd. (72) Inventor Makoto Shibuya 1006 Odaka Kadoma, Kadoma City, Osaka Pref. Document JP-A-50-74836 (JP, A) JP-A-61-74290 (JP, A) JP-A-3-104994 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05B 6/64-6/66

Claims (4)

(57) [Claims] A pulsating electric power obtained by rectifying a commercial power supply.
A power conversion unit that converts power supplied from an external power supply that outputs pressure, a radio wave radiation unit that receives an output of the power conversion unit and radiates high-frequency power to a heating chamber, and heating that controls a heating state of an object to be heated. A control unit, a storage battery configured to supply power to the power conversion unit, and a conversion power of the power conversion unit in a continuous operation state for a predetermined time according to an arbitrary command signal from the heating control unit. And a short-time high-power control unit that controls the power to be greater than the steady-state power of the power supply.The short-time high-power control unit controls the power conversion unit to control the power of both energy sources of the external power supply and the storage battery. A high-frequency heating device configured to supply to a conversion unit and control the radio wave output to be larger than a steady radio wave output in a continuous operation state for a predetermined time according to the command signal. 2. The short-time high-power control unit controls the power conversion unit in response to a start command signal from the heating control unit to reduce the power of both energy sources of the external power supply and the storage battery to the power supply. A configuration in which the short-time high-power control unit controls the converted power of the power conversion unit to be larger than the steady-state power in the continuous operation state during a predetermined time when the high-frequency heating device is activated. 2. The high-frequency heating apparatus according to claim 1, wherein the radio wave output at the time of startup for a predetermined time according to the command signal is controlled to be larger than the steady radio wave output in a continuous operation state. 3. The high-frequency heating apparatus according to claim 1, further comprising charging means for charging a storage battery by obtaining electric power from a commercial power supply. 4. The high-frequency heating apparatus according to claim 3, wherein the storage means is charged by the charging means when the operation of the power converter is stopped.